Updated results on atypical human trypanosomoses caused by animal trypanosomes

There are only two classical human forms of trypanosomoses, they are sleeping sickness in Africa (Trypanosoma brucei spp.) and Chagas' disease (T. cruzi) mainly in South America respectively. Other trypanosomes can infect a wide range of wild and domestic animals (fish, reptile, amphibians, mammals including cattle), but they are not supposed to be infective to human beings. However, several human cases infected by animal trypanosomes have been recently reported, in particular Trypanosoma lewisi (a Rattus trypanosome usually transmitted by fleas), and T. evansi (found for instance in cattle, camels, and mechanically transmitted by blood sucking insects such as tabanids or stomoxes). High density lipoprotein (HDL) in normal human serum (NHS) contains several compounds (e.g. ApoL-1) which protect us against African trypanosomes. The Indian patient infected with T. evansi reported in 2005 because of a genetic deletion was confirmed in the ApoL-1 gene in this patient, while another naturally T. evansi infected patient reported in Viet Nam in 2015 had a normal ApoL-1. The mode of transmission suspected in both cases was direct contamination via a wound while butchering raw beef. Both patients were cured successfully by using suramine, a drug for the acute form of sleeping sickness. Human infected with T. lewisi was mainly reported in babies. Although most of cases were transient infections, other required treatment or died. A recent case died from T. lewisi infection in India in 2015. It has been demonstrated that this parasite is resistant to NHS. Thus, T. lewisi is potentially a human pathogen or zoonotic pathogen. We present the new cases either described or suspected since the 2012, and previous cases as well (including infection by T. b. brucei, T. congolense). The problem of diagnosis and treatment will be considered, and the potential risk of emergence of a new zoonotic disease will be discussed

A preliminary serological study of Trypanosoma evansi and Trypanosoma lewisi in a Chinese human population

Trypanosoma evansi, known as an animal trypanosome, is widely distributed in many countries of Africa, Asia and South America; it causes significant economic loss in these countries. A few cases have also occurred in some countries of Europe due to the importation of infected animals from endemic regions. Rare human T. evansi infections were attended by the health departments and international health organizations in these endemic countries. Trypanosoma lewisi, a cosmopolitan parasite of rats, sometimes found in humans, is currently considered as a zoonotic pathogen and has gained special attention from scientists and international health organizations such as the World Health Organization. The current study considered the serological screening of human infection by T. evansi and T. lewisi in a Chinese human population. None of the 622 samples was found positive for T. evansi infection using the card agglutination test for the trypanosome antigen Rotat 1.2, while, 2.41% of the examined serum samples exhibited some seropositivity to T. lewisi using enzyme-linked immunosorbent assay. No significant difference was found between the samples from areas in the South (Zhaoqing, Guangdong) and Central (Zhengzhou, Henan) China

Trypanosoma evansi and Surra: A review and perspectives on transmission, epidemiology and control, impact, and zoonotic aspects

This paper reviews the transmission modes of Trypanosoma evansi. Its worldwide distribution is attributed to mechanical transmission. While the role of tabanids is clear, we raise questions on the relative role of Haematobia sp. and the possible role of Stomoxys sp. in delayed transmission. A review of the available trypanocidal drugs and their efficacy in various host species is useful for understanding how they interact in disease epidemiology, which is complex. Although there are similarities with other mechanically transmitted trypanosomes, T. evansi has a more complex epidemiology due to the diversity of its hosts and vectors. The impact of clinical and subclinical disease is difficult to establish. A model was developed for buffaloes in the Philippines, which could be transferred to other places and livestock systems. Since Trypanosoma evansi was reported in humans, further research is required to investigate its zoonotic potential. Surra remains a potentially emerging disease that is a threat to Australia, Spain, and France. A number of questions about the disease have yet to be resolved.This brief review of the basic knowledge of T. evansi suggests that there is renewed interest in the parasite, which is spreading and has a major economic impact. (Résumé d'auteur

High frequency detection of Toxoplasma gondii DNA in human neonatal tissue from Libya

Background: Toxoplasma gondii is a parasite that causes significant disease in humans. Toxoplasmosis is normally asymptomatic, unless associated with congenital transmission, or in immunocompromised people. Congenital transmission generally occurs at low frequencies. In this study, we use PCR to investigate possible congenital transmission of T. gondii during pregnancy in a cohort of mothers from Libya. Methods: Two hundred and seventy two pregnant women (producing 276 neonates) were recruited to obtain umbilical cord tissue from their neonates at birth. DNA was extracted from umbilical cord tissue and tested for T. gondii DNA using two specific PCR protocols based on the sag 1 and sag 3 genes. Results: Toxoplasma gondii DNA was detected in the umbilical cord DNA from 27 of the 276 neonates giving a prevalence of 9.9% (95% CI: 6.8-13.9%). Compared with more commonly reported rates of congenital transmission of 0.1% of live births, this is high. There was no association of infection with unsuccessful pregnancy. Conclusions: This study shows a high frequency presence of T. gondii DNA associated with neonatal tissue at birth in this cohort of 276 neonates from Libya. Although PCR cannot detect living parasites, there is the possibility that this indicates a higher than usual frequency of congenital transmission

TMRT observations of 26 pulsars at 8.6 GHz

Integrated pulse profiles at 8.6~GHz obtained with the Shanghai Tian Ma Radio Telescope (TMRT) are presented for a sample of 26 pulsars. Mean flux densities and pulse width parameters of these pulsars are estimated. For eleven pulsars these are the first high-frequency observations and for a further four, our observations have a better signal-to-noise ratio than previous observations. For one (PSR J0742-2822) the 8.6~GHz profiles differs from previously observed profiles. A comparison of 19 profiles with those at other frequencies shows that in nine cases the separation between the outmost leading and trailing components decreases with frequency, roughly in agreement with radius-to-frequency mapping, whereas in the other ten the separation is nearly constant. Different spectral indices of profile components lead to the variation of integrated pulse profile shapes with frequency. In seven pulsars with multi-component profiles, the spectral indices of the central components are steeper than those of the outer components. For the 12 pulsars with multi-component profiles in the high-frequency sample, we estimate the core width using gaussian fitting and discuss the width-period relationship.Comment: 33 pages, 49 figures, 5 Tables; accepted by Ap

Guanylate-binding Protein 1 (GBP1) contributes to the immunity of human mesenchymal stromal cells against toxoplasma gondii

Mesenchymal stromal cells (MSCs) have recently been shown to play important roles in mammalian host defenses against intracellular pathogens, but the molecular mechanism still needs to be clarified. We confirmed that human MSCs (hMSCs) pre-stimulated with IFN-γ showed a significant and dose-dependent ability to inhibit the growth of two types of Toxoplasma gondii (type I strain RH/GFP or type II strain PLK/RED). However, in contrast to previous reports, the anti-T. gondii activity of hMSCs was not mediated by indoleamine 2,3-dioxygenase (IDO). Genome-wide RNA-seq analysis revealed that IFN-γ increased the expression of the p65 family of guanylate-binding proteins (hGBPs) in hMSCs, especially hGBP1. To analyze the functional role of hGBPs, stable knockdowns of hGBP1, -2, -5 in hMSCs were established using a lentiviral transfection system. hGBP1 knockdown in hMSCs resulted in a significant loss of the anti-T. gondii host defense property, compared with hMSCs infected with non-targetted control sequences. hGBP2 and -5 knockdowns had no effect. Moreover, the hGBP1 accumulation on the parasitophorous vacuole (PV) membranes of IFN-γ-stimulated hMSCs might protect against T. gondii infection. Taken together, our results suggest that hGBP1 plays a pivotal role in anti-T. gondii protection of hMSCs and may shed new light on clarifying the mechanism of host defense properties of hMSCs

Erratum to : Analysis of the mitochondrial maxicircle of Trypanosoma lewisi, a neglected human pathogen

BACKGROUND The haemoflagellate Trypanosoma lewisi is a kinetoplastid parasite which, as it has been recently reported to cause human disease, deserves increased attention. Characteristic features of all kinetoplastid flagellates are a uniquely structured mitochondrial DNA or kinetoplast, comprised of a network of catenated DNA circles, and RNA editing of mitochondrial transcripts. The aim of this study was to describe the kinetoplast DNA of T. lewisi. METHODS/RESULTS In this study, purified kinetoplast DNA from T. lewisi was sequenced using high-throughput sequencing in combination with sequencing of PCR amplicons. This allowed the assembly of the T. lewisi kinetoplast maxicircle DNA, which is a homologue of the mitochondrial genome in other eukaryotes. The assembly of 23,745 bp comprises the non-coding and coding regions. Comparative analysis of the maxicircle sequence of T. lewisi with Trypanosoma cruzi, Trypanosoma rangeli, Trypanosoma brucei and Leishmania tarentolae revealed that it shares 78 %, 77 %, 74 % and 66 % sequence identity with these parasites, respectively. The high GC content in at least 9 maxicircle genes of T. lewisi (ATPase6; NADH dehydrogenase subunits ND3, ND7, ND8 and ND9; G-rich regions GR3 and GR4; cytochrome oxidase subunit COIII and ribosomal protein RPS12) implies that their products may be extensively edited. A detailed analysis of the non-coding region revealed that it contains numerous repeat motifs and palindromes. CONCLUSIONS We have sequenced and comprehensively annotated the kinetoplast maxicircle of T. lewisi. Our analysis reveals that T. lewisi is closely related to T. cruzi and T. brucei, and may share similar RNA editing patterns with them rather than with L. tarentolae. These findings provide novel insight into the biological features of this emerging human pathogen